1. Field of the Invention
The present invention relates generally to laser machining. More specifically, it pertains to a pulsed laser ablation method of films from the surface of a semi-conducting wafer, printed circuit board or a hybrid substrate and/or to the substrate without affecting the material adjacent to the ablation zone.
2. State of Technology
In defining films on electronic circuits, the present state-of-the-art process is to use a physical mask to define the metal or dielectric film by photolithographic processes. However, the use of such physical masks can produce non-uniformities in the desired structures of the films due to: undercutting of the metal films by required acid etching techniques, the requirement of a lift-off process because the dielectric film cannot be etched, films that require heating may result in a damaged photo-resist, and turn-around times for producing the physical mask being up to several weeks.
However, lasers may be utilized to overcome such problems and define such films on electronic circuits. Such lasers have previously been used to machine or cut a target comprised of a rigid material, such as metals, wood, rubber or plastics. Lasers machine or cut such materials by inducing a breakdown of the material through chemical and physical breakdown, vaporization, and ablation. Pulsed lasers have been utilized to selectively ablate material from such targets by outputting pulses of light having pulse durations of less than nanoseconds.
Accordingly, there is a need in industry for utilizing pulsed lasers, in particular, ultra-short pulsed lasers having temporal pulse durations of less than about 1 picosecond to define features on films arranged on substrates.